Control systems have long been used to cause the opening and closing of a valve. Present day systems utilize fluid-pressure-activated actuators, which cause longitudinal or oscillatory movement of a valve stem, thereby effecting such opening and closing. Such pressure, is provided by a supply source. Intermediate such source and actuator, there may be pilot-control devices, which permit the passage of such motivating fluid only when the pressure of the supply is within a discreet range. It has been deemed beneficial to provide additional controls, intermediate such supply and actuator, to permit bleeding of fluid from the actuator, in the event of valve closure. It is to the solution of the latter mentioned problem that this invention is directed.